Even without breaches, don’t count on websites to hide that you have an account with them
Companies often fail to hide if an email address is associated with an account on their websites, even if the nature of their business calls for this and users implicitly expect it.
This has been highlighted by data breaches at online dating sites AdultFriendFinder.com and AshleyMadison.com, which cater to people looking for one-time sexual encounters or extramarital affairs. Both were vulnerable to a very common and rarely addressed website security risk known as account or user enumeration.
In the Adult Friend Finder hack, information was leaked on almost 3.9 million registered users, out of the 63 million registered on the site. With Ashley Madison, hackers claim to have access to customer records, including nude pictures, conversations and credit card transactions, but have reportedly leaked only 2,500 user names so far. The site has 33 million members.